American Society of Heating, Refrigerating, and Air-Conditioning Engineers

From pandemic to seasonal, the COVID-19 pandemic experience suggests many common respiratory infections rather than likely having a fomite etiology as previously thought, are primarily caused by the inhalation of infectious aerosols shed by ill persons during coughing and normal breathing and talking. Given this new understanding, the good news is that, unlike indoor-sourced noxious and irritating gases that can only be mitigated practically by diluting them with outdoor air ventilation, the indoor infectious aerosol illness transmission route can be addressed by circulating already conditioned air through commonplace commercial filters. Given that infectious aerosols released from the breath of occupants were practically an unknown vector of respiratory disease in the healthcare community for many decades, understandably HVAC regulations have not addressed this issue yet. However, this is about to change. To further this new end, this paper develops the formulae needed to set conditioned air recirculation rates through such filters for design infectious aerosol emission and inhalation rates, HID values, exposure times and occupancies, and target significantly lower than currently normal airborne infection reproduction rates. The analysis extends the equations previously developed for group inhalation of infectious aerosols to develop equations predicting the number of infections likely to occur from this inhalation and the rate of disease spread (reproduction). The governing equations provided and exemplified use group exposures since the number of infections (reproduction number) is group based. Examples using the equations provided are given for many different settings and two case study findings are compared with their predictions. Some settings such as the typical office are shown to already have a relatively low infection reproduction rate. Alternatively, others such as a typical school classroom or a longer commercial air flight require increased filtered ventilation air flows to yield a similarly low reproduction rate. The formulae and their application will be of interest to government and industry health and HVAC standard setting bodies.

The Army's critical missions are at risk from interruption of water supplies.Sufficient amounts of high-quality potable water are a resource without

This special edition of the Science and Technology for the Built Environment (STBE) presents eight selected articles originally presented at the 17th International Refrigeration and Air Conditionin...

The present work focuses on the improvement of the ideal Rankine cycle performance used in steam power plants. Improving the steam power plant efficiency, or its components performance is desirable where the absence of renewable energy power conversion systems and the shortage of conventional fuels sources take place. The present work studies the possibility of using a counter flow heat exchanger along with the main components of the ideal Rankine cycle. The proposed counter flow heat exchanger will include the flow of compressed liquid exiting the pump and the flow of superheated steam exiting the steam turbine. The advantages of the proposed system which is investigated here include extracting heat through the heat exchanger which can be added to boiler for superheated steam production and thus reduce the amount fuel needed. In addition, since the proposed system assumes a superheated steam at the exit of the steam turbine, so no moisture is expected to form and thus increased effeciency of the steam turbine will be expected. The presents results show that the amount of heat extracted through the proposed heat exchanger for diffrent systematic four test cases of differet exits' temperatures of steam turbines and heat exchanger is systematically increasing when the those temperatures are decreasing suggesting the advantage of the proposed heat exchanger. In addition, however the proposed system eliminated the presence of moisture at the steam turbine which improve the performance of the steam turbine, a systematic reduction reduction in the delivered work by the steam turbine

Countries, states, and cities around the world are seeking to enhance power sector resilience through a combination of policy and technology. However, few of these efforts fully incorporate the built environment into power sector planning. Buildings account for more than a third of the global annual energy consumption and more than 60% of the annual electricity consumption. As such, buildings play a critical role in enhancing resilience in the power sector. Buildings can aid in power sector resilience by increasing power system flexibility, shaving and shifting demand, and providing on-site energy generation. All of these strategies require incentives to encourage participation. This paper presents an overview of energy management strategies to better incorporate building design and operation in power sector resilience planning.

Background: Indoor air pollution contains several substances and can emanate from a range of sources. In particular importance might be substances known as volatile organic compounds and respirable particulates. The exposure to indoor air pollution can induce a wide range of acute and chronic respiratory health effects. The study's aims were to identify the effect of indoor air pollution sources and concentrations in offices on respiratory health of occupants and identify potential factors that may be related to respiratory health problems.
 
 Methods: Fourteen offices were measured the concentration of PM2.5 and TVOC at 1.20 meters high for 8 hours and office characteristics such as building age, floor and furnishing materials, room volume were observed together with number of computers, printers and photocopiers. The 212 occupants in these offices were questioned and tested the lung function. The subjective respiratory symptoms were cough, phlegm, wheezing and short breathing. Focus group discussions was conducted with twelve occupants with abnormal lung function and symptoms
 
 Results: Two hundred and twelve occupants mostly are female, nonsmoker and age average 34.61 ? 7.501 years old. They mostly report no history in medical records and history in dusty job, gas or volatile job and fume job. Quarter of them have over ten year experience in current job and two third work more than eight hour a day. The age of office buildings are 8-26 years. Floor materials are tile, rubber, carpet and furnishing materials are MDF, cement, gypsum, glass and metal. The most number of computers, printer and photocopiers is 50, 28 and 3 sets respectively. The mean concentration of PM2.5 in these offices is 0.026 ? 0.006 mg/m3 and in range of 0.015 - 0.039 mg/m3. The mean concentration of TVOC in these offices is 156.38 ? 59.34 ppb and in range of 45.33 – 260.67 ppb. The prevalence of restrictive lung function, obstructive lung function and combined are 236, 28 and 28 cases per thousand persons respectively and the prevalence of cough, phlegm, wheezing and short breathing are 255, 160, 184 and 156 cases per thousand persons respectively. The logistic regression analysis shows that concentration of TVOC was significantly associated with FVC and wheeze symptoms (p-value < 0.05), concentration of PM2.5 was significantly associated with FEV1/FVC (p-value < 0.05) and smoking was significantly associated with cough (p-value < 0.05). The significantly association between history in gas/volatile job and phlegm, current work experience and FEV1/FVC were found. The odds of restrictive abnormal lung function were 9.289 times higher in high TVOC exposure and 0.110 times lower in the large office. The odds of obstructive abnormal lung function were 3.588 times higher in the high PM2.5 exposure and 3.407 times higher in longer experience in current job. The odds of cough were 2.438 times higher in smoker. The odds of phlegm were 4.184 times higher in former exposure in gas or volatile. The odds of wheezing were 3.196 times higher in the high TVOC exposure. The odds of short breathing were 2.791 times higher in female.
 
 Conclusion: Indoor air pollution exposure can risk the respiratory health effects. Smoking and work experience also affect to the respiratory health. The risk of occupational respiratory health may decrease if indoor air pollution become lower.�

Degree-days techniques are fundamental steady state methods for cooling frameworks analysis. The significance of such techniques shows up in the most recent couple of decades where vitality consumption increments altogether while the world energy assets turn out to be rare. Additionally, these techniques can provide a straightforward approach for the estimation of monthly or annual energy consumptions of air conditioning systems.The issue of building up a cooling degree-days unit for summer air conditioning systems similar to that for heating system has been entangled by the way that energy consumption for summer air conditioning systems is influenced not just by sensible heat transmission (because of dry bulb temperature contrast) but additionally by latent heat load. Endeavors, have been done to make sense of a cooling degree-days unit by including the estimations of the inconvenience list (incorporates both dry bulb and wet bulb temperatures with certain weights) at different time periods daily, then subtracting certain value (usually called base temperature) from this sum.This requires comprehensive temperature records and does not take into account the internal sources of the latent loads (inhabitants, supplies, and so on). Another intricacy is the effect of solar radiation on cooling loads, which is not directly related to any of the ambient temperatures. Besides, many works exhibited comes about for cooling degree-days units utilizing wet bulb temperatures only.In this work, cooling degree-days models are exhibited and connected to most cities in Egypt covering every climatic zone of the country. The models considers the impact of both the sensible heat transmission and the latent (inward and outside) cooling load. They additionally consider the impact of solar heat gain on the cooling degree-days unit. What's more, the impact of base temperature is examined. Correlations between the consequences of the introduced model and cooling degree-days units computed from direct surrounding temperature records are shown.

Many interpretations of what building information modeling (BIM) is and what implications it may have on the wider construction industry have been published; yet, there is still ambiguity about wha...